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GHSA-CRQ7-3PJ4-2VVG

Vulnerability from github – Published: 2026-09-16 12:30 – Updated: 2026-09-16 12:30

Details

In the Linux kernel, the following vulnerability has been resolved:

KVM: arm64: Handle VNCR TLB invalidation race with vcpu_put() VNCR unmapping

While VNCR TLB invalidation always occurs under the MMU lock, vcpu_put() doesn't, while it unmaps the VNCR page.

The problem is that the invalidation evaluates vncr_tlb::cpu to decide whether an unmapping needs to take place (cpu != -1) before performing it. On the other hand, this_cpu_reset_vncr_fixmap() unconditionally unmaps if L1_VNCR_MAPPED is set.

These two obviously can race, with a TOCTOU pattern on the TLBI path, and a BUG_ON() on the vcpu_put() path. And the two can end-up calling vncr_fixmap(-1), with extra lethal effects.

Move the reset of vncr_tlb::cpu to -1 to a common function, and make this update atomic so that only a single thread can reset the field and perform the corresponding unmap. The vcpu_put() still need to unconditionally unmap the current VNCR to close another ugly race.

Finally, the assignment of vncr_tlb::cpu is moved to be kept in sync with the actual mapping, similar to L1_VNCR_MAPPED being set.

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{
  "affected": [],
  "aliases": [
    "CVE-2026-89917"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-09-16T11:17:00Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: arm64: Handle VNCR TLB invalidation race with vcpu_put() VNCR unmapping\n\nWhile VNCR TLB invalidation always occurs under the MMU lock,\nvcpu_put() doesn\u0027t, while it unmaps the VNCR page.\n\nThe problem is that the invalidation evaluates vncr_tlb::cpu to\ndecide whether an unmapping needs to take place (cpu != -1) before\nperforming it. On the other hand, this_cpu_reset_vncr_fixmap()\nunconditionally unmaps if L1_VNCR_MAPPED is set.\n\nThese two obviously can race, with a TOCTOU pattern on the TLBI\npath, and a BUG_ON() on the vcpu_put() path. And the two can end-up\ncalling vncr_fixmap(-1), with extra lethal effects.\n\nMove the reset of vncr_tlb::cpu to -1 to a common function, and make\nthis update atomic so that only a single thread can reset the field\nand perform the corresponding unmap. The vcpu_put() still need to\nunconditionally unmap the current VNCR to close another ugly race.\n\nFinally, the assignment of vncr_tlb::cpu is moved to be kept in sync\nwith the actual mapping, similar to L1_VNCR_MAPPED being set.",
  "id": "GHSA-crq7-3pj4-2vvg",
  "modified": "2026-09-16T12:30:41Z",
  "published": "2026-09-16T12:30:41Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-89917"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/38640bc32be3fcf9526d477155bc19d3f146231f"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/5cbd8761d001c11ada73b1753d772c4745a70e72"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/9065c1261f8a05c6a7a2d90048c7c0665ab2896d"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}

CVE-2026-89917 (GCVE-0-2026-89917)

Vulnerability from cvelistv5 – Published: 2026-09-16 10:32 – Updated: 2026-09-16 10:32

Title

KVM: arm64: Handle VNCR TLB invalidation race with vcpu_put() VNCR unmapping

Summary

In the Linux kernel, the following vulnerability has been resolved: KVM: arm64: Handle VNCR TLB invalidation race with vcpu_put() VNCR unmapping While VNCR TLB invalidation always occurs under the MMU lock, vcpu_put() doesn't, while it unmaps the VNCR page. The problem is that the invalidation evaluates vncr_tlb::cpu to decide whether an unmapping needs to take place (cpu != -1) before performing it. On the other hand, this_cpu_reset_vncr_fixmap() unconditionally unmaps if L1_VNCR_MAPPED is set. These two obviously can race, with a TOCTOU pattern on the TLBI path, and a BUG_ON() on the vcpu_put() path. And the two can end-up calling vncr_fixmap(-1), with extra lethal effects. Move the reset of vncr_tlb::cpu to -1 to a common function, and make this update atomic so that only a single thread can reset the field and perform the corresponding unmap. The vcpu_put() still need to unconditionally unmap the current VNCR to close another ugly race. Finally, the assignment of vncr_tlb::cpu is moved to be kept in sync with the actual mapping, similar to L1_VNCR_MAPPED being set.

Severity

No CVSS data available.

Assigner

Linux mitre root

References

3 references

URL	Tags
https://git.kernel.org/stable/c/5cbd8761d001c11ad…
https://git.kernel.org/stable/c/9065c1261f8a05c6a…
https://git.kernel.org/stable/c/38640bc32be3fcf95…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 7270cc9157f474dfc46750a34c9d7defc686b2eb , < 5cbd8761d001c11ada73b1753d772c4745a70e72 (git) Affected: 7270cc9157f474dfc46750a34c9d7defc686b2eb , < 9065c1261f8a05c6a7a2d90048c7c0665ab2896d (git) Affected: 7270cc9157f474dfc46750a34c9d7defc686b2eb , < 38640bc32be3fcf9526d477155bc19d3f146231f (git)
Linux	Linux	Affected: 6.16 Unaffected: 0 , < 6.16 (semver) Unaffected: 6.18.52 , ≤ 6.18.* (semver) Unaffected: 7.2.5 , ≤ 7.2.* (semver) Unaffected: 7.3-rc1 , ≤ * (original_commit_for_fix)

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "arch/arm64/kvm/nested.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "5cbd8761d001c11ada73b1753d772c4745a70e72",
              "status": "affected",
              "version": "7270cc9157f474dfc46750a34c9d7defc686b2eb",
              "versionType": "git"
            },
            {
              "lessThan": "9065c1261f8a05c6a7a2d90048c7c0665ab2896d",
              "status": "affected",
              "version": "7270cc9157f474dfc46750a34c9d7defc686b2eb",
              "versionType": "git"
            },
            {
              "lessThan": "38640bc32be3fcf9526d477155bc19d3f146231f",
              "status": "affected",
              "version": "7270cc9157f474dfc46750a34c9d7defc686b2eb",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "arch/arm64/kvm/nested.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.16"
            },
            {
              "lessThan": "6.16",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.52",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.5",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3-rc1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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                  "versionStartIncluding": "6.16",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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                  "versionStartIncluding": "6.16",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3-rc1",
                  "versionStartIncluding": "6.16",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: arm64: Handle VNCR TLB invalidation race with vcpu_put() VNCR unmapping\n\nWhile VNCR TLB invalidation always occurs under the MMU lock,\nvcpu_put() doesn\u0027t, while it unmaps the VNCR page.\n\nThe problem is that the invalidation evaluates vncr_tlb::cpu to\ndecide whether an unmapping needs to take place (cpu != -1) before\nperforming it. On the other hand, this_cpu_reset_vncr_fixmap()\nunconditionally unmaps if L1_VNCR_MAPPED is set.\n\nThese two obviously can race, with a TOCTOU pattern on the TLBI\npath, and a BUG_ON() on the vcpu_put() path. And the two can end-up\ncalling vncr_fixmap(-1), with extra lethal effects.\n\nMove the reset of vncr_tlb::cpu to -1 to a common function, and make\nthis update atomic so that only a single thread can reset the field\nand perform the corresponding unmap. The vcpu_put() still need to\nunconditionally unmap the current VNCR to close another ugly race.\n\nFinally, the assignment of vncr_tlb::cpu is moved to be kept in sync\nwith the actual mapping, similar to L1_VNCR_MAPPED being set."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-16T10:32:12.629Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
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          "url": "https://git.kernel.org/stable/c/5cbd8761d001c11ada73b1753d772c4745a70e72"
        },
        {
          "url": "https://git.kernel.org/stable/c/9065c1261f8a05c6a7a2d90048c7c0665ab2896d"
        },
        {
          "url": "https://git.kernel.org/stable/c/38640bc32be3fcf9526d477155bc19d3f146231f"
        }
      ],
      "title": "KVM: arm64: Handle VNCR TLB invalidation race with vcpu_put() VNCR unmapping",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-89917",
    "datePublished": "2026-09-16T10:32:12.629Z",
    "dateReserved": "2026-09-11T19:38:34.775Z",
    "dateUpdated": "2026-09-16T10:32:12.629Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

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Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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GHSA-CRQ7-3PJ4-2VVG

CVE-2026-89917 (GCVE-0-2026-89917)

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